Abstract:
This study is aimed to assess the performance of flex bag digester according using
different performance parameters; the capacity of the digester was 2000 Liters with
working volume of 1500 Liters. The performance parameters assessed were technical
performance parameters include temperature fluctuation, pH levels and gas production per
kg of feedstock, operational performance parameters include cleanliness of the site and
ease of use, economic performance parameters include investment cost, operational cost ,
and social, environmental parameters include stove and lamp use, and firewood saving.
Two kinds of feedstocks were used in the study Cow dung feedstock and food waste
feedstock with a dry matter of 20 percent and 50 percent respectively, the average feeding
of cow dung feedstock was about 19kg per day, and 10 kg per day for the food waste
feedstock. The retention time of the feedstocks was found to be 40 days and 30 days
respectively, with potential gas production of 32 Liters per kg of cow dung and 194 Liters
per kg of food waste. The absence of an inlet mixing tank at the inlet makes feeding it more
cumbersome and also increases the likelihood of spillage of the mixture around the inlet of
the biodigester. The produced biogas was used in cooking stove for cooking different types
of food. It found that the consumption of biogas is proportionally changes with change of
cooking time and the pressure inside the digester.
